Just thinking if there is an advantage adding an alternator to my charging system. Right now I have a house bank of 770 AH and I'm charging it off my generator with a heart 3000 watt charger/inverter I beleive the charger is 150 amp. Would there be any advantage adding a high power alternator to the generator and charge the batteries or just stay with the inverter/charger. Any thoughts?

You would get a boost at the beginning of your charging cycle but would soon reach a point where the alternator wouldn't be contributing much, if any. You certainly wouldn't need a high capacity alternator. 25% of 770 amps is about 190 amps. So if your Inverter/Charger puts out 150 amps. you only need to make up 40 - 45 amps. An 80 amp alternator would be a good size. Make sure your regulator / charger are temp. compensated with temp. sensors on your batteries.

Edit: I'm not sure if there would be any negative interaction in your regulator. Probably not but maybe there is someone that has done this on the forum.

Captden,
We have a Kubota genset and a hart inverter charger (2500 watt / 130 amp charger). My house battery bank consist of 8 T105 batteries (900 amphours @ 12v). I also have 110v referigeration and a 110v watermaker. While crusing, I usually run the referigation an hour in the morning from the batteries (using the inverter) then in the afternoon we run the genset an hour or so to charge the batteries, run the refrigeration and run the watermaker. I also have a 125 amp alternator which is NOT installed on the genset .... it IS installed on the main engine. If we motor during the day we can easily charge the batteries, run the refrigeration or run the watermaker and eliminate the afternoon genset running. While I think a large alternator would be usefull on your main engine I don't think a high amp alternator on your genset would be worth the cost.

Well...you already have an alternator...just not a big one...so you can certainly keep the batteries charged in the event of a generator breakdown...though it may take some time to do so.
The only real justification for the significant added expense of a high output alternator and 3 stage regulator is if you motor a lot and would rather take advantage of that instead of running a generator later on. Obviously...you don't want to charge your batteries WITH the generator THEN go motoring. You'd want to run them down to 50% then go motoring with nearly 400 amp hours to replace which could mostly be done in about 4 hours off a 100-120amp alternator.
If that sounds like a realistic scenario to you then it may be worth it to upgrade the alternator. Otherwise stick with the genset and use current alternator just to top off the charging occasionally.

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